Wednesday, 3 July 2013

trigonometry - How to compute cos(pi/3) with Angle sum and difference identities?


How to compute cos(π/3) with Angle sum and difference

identities?




Hello. I am only allowed to use the Pythagorean trigonometric identity, Angle sum and difference identities, and the fact that sine and cosine are periodic functions with period 2π.



I tried it like this: cos(π/3)=cos(π/6+π/6)=cos(π/6)cos(π/6)sin(π/6)sin(π/6)=cos2(π/6)sin2(π/6) Can I now somehow make use of the Pythagorean trigonometric identity?

No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find lim without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...